Semiconductor device and method of manufacturing the same

ABSTRACT

A semiconductor chip is sealed by resin without covering an outer terminal of a semiconductor device having a power transistor. A semiconductor chip having a power transistor is housed within a recess of a metal cap while a drain electrode on a first surface of the semiconductor chip is bonded to a bottom of the recess via a connection material. A gate electrode and a source electrode are formed on a second surface opposite to the first surface of the semiconductor chip, and the gate electrode and the source electrode are bonded with metal plate terminals  6 G,  6 S via connection materials  5   b,    5   c . In addition, the semiconductor chip is sealed by a resin sealing body with mounting-surfaces of the metal plate terminals  6 G,  6 S being exposed. Mounting surfaces of the metal plate terminals  6 G,  6 S and a third part of the metal cap are bonded to electrodes on a mounting board  10  via connection materials  5   e,    5   f  and  5   g.

This application is a continuation application of U.S. application Ser.No. 11/783,919, filed Apr. 13, 2007, which is a divisional applicationof U.S. application Ser. No. 11/349,219, filed Feb. 8, 2006, now U.S.Pat. No. 7,220,617, the entirety of which is incorporated herein byreference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a semiconductor device and a method formanufacturing the device, particularly relates to a packaging techniqueof a semiconductor device having a power transistor.

2. Description of Related Art

A high-power semiconductor device includes a semiconductor device havinga semiconductor chip in which a power transistor such as power MOSFET(Metal Oxide Semiconductor Field-Effect-Transistor), IGBT (InsulatedGate Bipolar Transistor), and bipolar power transistor is formed.

The semiconductor device having such a power transistor is described in,for example, International Patent Application No. W2001/075961 (patentliterature 1) which discloses a structure of a semiconductor devicehaving the power MOS FET. The paragraph 0024 and FIG. 21 of the patentliterature 1 disclose a configuration in which a drain electrode of adie (semiconductor chip) is connected to a surface of an inner web in aclip by epoxy containing silver, and optimally epoxy having low stressand high adhesive force is coated around an edge of a die in a ringpattern to seal a package and add structural strength to the package.

Moreover, for example, JP-A-2003-51513 (patent literature 2) discloses aconfiguration in which an electrode of a semiconductor chip having apower MOS FET is connected with a metal strip. The paragraph 0041 andFIG. 5 of the patent literature 2 disclose a configuration in which themetal strip is directly bonded onto an electrode pad of a semiconductordevice (semiconductor chip) using ultrasonic energy, and furthermoreperiphery of the bonded portion between the electrode pad and the metalstrip is sealed by moisture-resistant resin having flexibility, moistureresistance and heat resistance.

[Patent literature 1] International Patent Application No. W 2001-075961(paragraph 0024 and FIG. 20).

[Patent literature 2] JP-A-2003-51513 (paragraph 0012, 0041, FIG. 5 andthe like).

SUMMARY OF THE INVENTION

However, the inventors found that the semiconductor device having thepower transistor had the following problems.

That is, first, there is a problem that filling control of the resin forsealing the semiconductor chip is difficult. When a surface of thesemiconductor chip is exposed, a problem on environmental-stressresistance such as leakage defect (particularly, area short at the outercircumferential portion of the semiconductor chip) or corrosion mayoccur. Therefore, the semiconductor chip is preferably sealed by resin,however, when the semiconductor chip as a whole is covered with resin,the resin may concernedly cover surfaces of source and gate electrodesof the semiconductor chip, or contaminate them, and therefore fillingcontrol of resin for sealing the semiconductor chip, or control of asurface level of the resin is difficult, and actually only a limitedarea of side faces and the like of the semiconductor chip can becovered. Since reduction in thickness of package tends to be furtheradvanced hereinafter, such a problem will be increasingly significant.

Second, there is a problem that outer terminals for a gate and a sourceof the semiconductor device vary depending on chip size of thesemiconductor chip, or positions or size of the gate and sourceelectrodes of the semiconductor chip. That is, in the case that the gateand source electrodes of the semiconductor chip are formed directly asouter terminals for the gate and source of the semiconductor device,even in the same semiconductor device, when the semiconductor chipvaries, the positions or size of the outer terminals for the gate andsource of the semiconductor chip may also vary.

Third, there is a problem that since the semiconductor chip is directlyconnected to a mounting board having larger heat conductivity than thesemiconductor chip, a connection portion for connecting the source andgate electrodes of the semiconductor chip to electrodes of the mountingboard is applied with large thermal stress, and therefore thermalfatigue occurs early in the connection portion, consequently theconnection portion is broken.

An object of the invention is to provide a technique that can seal thesemiconductor chip by resin without covering the outer terminals of thesemiconductor device having the power transistor.

Another object of the invention is to provide a technique that can addversatility to an electrode configuration of the semiconductor devicehaving the power transistor.

Another object of the invention is to provide a technique that canimprove a thermal fatigue life of the connection portion between thesemiconductor device having the power transistor and the mounting board.

The above and other objects and novel features of the invention will beclarified according to description of the specification and accompanieddrawings.

Summary of typical one of the inventions disclosed in the application isbriefly described as follows.

Thus, in the invention, a metal plate terminal is provided on anelectrode on a surface, which faces a mounting board, of a semiconductorchip housed in a recess of a metal cap via a connection material, andthe semiconductor chip is sealed by a resin sealing body such that themetal plate terminal is exposed.

ADVANTAGE OF THE INVENTION

Advantageous effects obtained from the typical one of the inventionsdisclosed in the application is briefly described as follows.

That is, the metal plate terminal is provided on the electrode on thesurface, which faces the mounting board, of the semiconductor chiphoused in the recess of the metal cap via the connection material, andthe semiconductor chip is sealed by the resin sealing body such that themetal plate terminal is exposed, thereby in the semiconductor devicehaving the power transistor, the semiconductor chip can be sealed byresin without covering the electrode of the semiconductor device.

Moreover, the metal plate terminal is provided on the electrode on thesurface, which faces the mounting board, of the semiconductor chiphoused in the recess of the metal cap via the connection material,thereby the electrode configuration of the semiconductor device havingthe power transistor can be provided with versatility.

The metal plate terminal is provided on the electrode on the surface,which faces the mounting board, of the semiconductor chip housed in therecess of the metal cap via the connection material, thereby the thermalfatigue life of the connection portion between the semiconductor devicehaving the power transistor and the mounting board can be improved.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view of a top of a semiconductor device of anembodiment of the invention;

FIG. 2 is a side view of the semiconductor device of FIG. 1;

FIG. 3 is a plan view of a bottom of the semiconductor device of FIG. 1;

FIG. 4 is a cross section view along a line X1-X1 of the semiconductordevice of FIG. 1;

FIG. 5 is a side view showing an example of mounting the semiconductordevice of FIG. 1;

FIG. 6 is a plan view of a top during mounting the semiconductor deviceof FIG. 5;

FIG. 7 is a cross section view along a line X2-X2 of the semiconductordevice of FIG. 6;

FIG. 8 is a plan view of a semiconductor chip forming the semiconductordevice of FIG. 1;

FIG. 9 is a cross section view along a line X3-X3 of the semiconductordevice of FIG. 8;

FIG. 10 is an enlarged section view of a power transistor cell of thesemiconductor device of FIG. 8;

FIG. 11 is a circuit diagram of an example of a non-insulated DC-DCconverter formed using the semiconductor device of FIG. 1;

FIG. 12 is a timing chart of an example of a signal of the non-insulatedDC-DC converter of FIG. 11;

FIG. 13 is views, wherein the upper is a plan view of the semiconductordevice of FIG. 1 during a manufacturing process, and the lower is across section view along a line X4-X4 of the upper;

FIG. 14 is views showing a manufacturing step of the semiconductordevice following FIG. 13, wherein the upper is a plan view of thesemiconductor device during the manufacturing process, and the lower isa cross section view along a line X4-X4 of the upper;

FIG. 15 is views showing a manufacturing process of the semiconductordevice following FIG. 14, wherein the upper is a plan view of thesemiconductor device during the manufacturing process, and the lower isa cross section view along a line X4-X4 of the upper;

FIG. 16 is views showing a manufacturing process of the semiconductordevice following FIG. 15, wherein the upper is a plan view of thesemiconductor device during the manufacturing process, and the lower isa cross section view along a line X4-X4 of the upper;

FIG. 17 is views showing a manufacturing process of the semiconductordevice following FIG. 16, wherein the upper is a plan view of thesemiconductor device during the manufacturing process, and the lower isa cross section view along a line X4-X4 of the upper;

FIG. 18 is views showing a manufacturing process of the semiconductordevice following FIG. 17, wherein the upper is a plan view of thesemiconductor device during the manufacturing process, and the lower isa cross section view along a line X4-X4 of the upper;

FIG. 19 is views showing a manufacturing process of the semiconductordevice following FIG. 18, wherein the upper is a plan view of thesemiconductor device during the manufacturing process, and the lower isa cross section view along a line X4-X4 of the upper;

FIG. 20 is a plan view of a top of a semiconductor device as anotherembodiment of the invention;

FIG. 21 is a side view of the semiconductor device of FIG. 20;

FIG. 22 is a plan view of a bottom of the semiconductor device of FIG.20;

FIG. 23 is a cross section view along a line X5-X5 of the semiconductordevice of FIG. 20;

FIG. 24 is a cross section view along a line Y1-Y1 of the semiconductordevice of FIG. 20;

FIG. 25 is a plan view showing an example of mounting the semiconductordevice of FIG. 20;

FIG. 26 is a side view of the semiconductor device of FIG. 25 duringmounting;

FIG. 27 is views, wherein the upper is a plan view of the semiconductordevice of FIG. 20 during a manufacturing process, and the lower is across section view along a line X6-X6 of the upper;

FIG. 28 is views showing a manufacturing process of the semiconductordevice following FIG. 27, wherein the upper is a plan view of thesemiconductor device during the manufacturing process, and the lower isa cross section view along a line X6-X6 of the upper;

FIG. 29 is views showing a manufacturing process of the semiconductordevice following FIG. 28, wherein the upper is a plan view of thesemiconductor device during the manufacturing process, and the lower isa cross section view along a line X6-X6 of the upper;

FIG. 30 is views showing a manufacturing process of the semiconductordevice following FIG. 29, wherein the upper is a plan view of thesemiconductor device during the manufacturing process, and the lower isa cross section view along a line X6-X6 of the upper;

FIG. 31 is a plan view of a top of a semiconductor device as stillanother embodiment of the invention;

FIG. 32 is a side view of the semiconductor device of FIG. 31;

FIG. 33 is a plan view of a bottom of the semiconductor device of FIG.31;

FIG. 34 is views, wherein the upper is a plan view of the semiconductordevice of FIG. 31 during a manufacturing process, and the lower is across section view along a line X7-X7 of the upper;

FIG. 35 is views showing a manufacturing process of the semiconductordevice following FIG. 34, wherein the upper is a plan view of thesemiconductor device during the manufacturing process, and the lower isa cross section view along a line X7-X7 of the upper;

FIG. 36 is views showing a manufacturing process of the semiconductordevice following FIG. 35, wherein the upper is a plan view of thesemiconductor device during the manufacturing process, and the lower isa cross section view along a line X7-X7 of the upper;

FIG. 37 is views showing a manufacturing process of the semiconductordevice following FIG. 36, wherein the upper is a plan view of thesemiconductor device during the manufacturing process, and the lower isa cross section view along a line X7-X7 of the upper; and

FIG. 38 is views showing a manufacturing process of the semiconductordevice following FIG. 37, wherein the upper is a plan view of thesemiconductor device during the manufacturing process, and the lower isa cross section view along a line X7-X7 of the upper.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

While the following embodiments are described with being divided intoseveral sections or embodiments if necessary for convenience, they arenot independent of one another except for a particularly specified case,and in a relation that one is a modification, detail, or supplementaryexplanation of part or all of the other. Moreover, when the followingembodiments refer to the number of elements (including number, numeralvalue, amount, and range), the number is not limited to the particularnumber and may be the particular number or more or less, except for aparticularly specified case and a case that it is principally obviouslylimited to a particular number. Furthermore, it is appreciated in thefollowing embodiments that components (including the number of elementsteps) of them are not necessarily indispensable except for aparticularly specified case and a case that it is considered to beprincipally obviously indispensable. Similarly, the followingembodiments are assumed to include those, which are substantially akinor similar to the embodiments in shapes and the like, except for aparticularly specified case and a case that it is considered to beprincipally obviously not akin or similar to them. Regarding the numeralvalue and the range, they are similarly assumed. Same reference signsare marked with those having the same function in all figures forexplaining the embodiments so that repeated description is not made aslong as possible. Hereinafter, embodiments of the invention will bedescribed in detail according to drawings.

Embodiment 1

FIG. 1 is a plan view of a top of a semiconductor device of embodiment1, FIG. 2 is a side view of the semiconductor device of FIG. 1, FIG. 3is a plan view of a bottom of the semiconductor device of FIG. 1, andFIG. 4 is a cross section view along a line X1-X1 of the semiconductordevice of FIG. 1.

The semiconductor device 1A of the embodiment 1 has a metal cap(conductive cap) 2, semiconductor chip 3 housed in a recess 2 a of themetal cap 2, and resin sealing body 4 for sealing the semiconductor chip3 filled in the recess 2 a of the metal cap 2.

The metal cap 2 comprises a metal having excellent electricconductivity, heat conductivity, and machinability such as copper orcopper alloys, and an exposed surface of it is applied with metalplating such as palladium (Pd) plating, lead (Pb)-tin (Sn) plating,tin-silver (Ag)-copper plating, or tin plating. The metal cap 2integrally has a first part (upper part) 2 b, second part (side part) 2c, and third part (leg part) 2 d.

The first part 2 b of the metal part 2 is a part forming a head of themetal cap 2 and a bottom of the recess 2 a. The second part 2 c of themetal cap 2 is a part forming the side part of the metal cap 2 and aninner side part of the recess 2 a. The second part 2 c is formed in acondition of extending from the outer circumference of the first part 2b in a direction intersecting (approximately perpendicular to) a top ofthe metal cap 2. The recess 2 a is formed in a space (region) enclosedby the first part 2 b and the second part 2 c. Furthermore, the thirdpart 2 d of the metal cap 2 is a part forming the leg of the metal cap2. That is, the third part 2 d is a part forming an outer terminal for adrain of the semiconductor device 1A, and a part to be connected with anelectrode of a mounting board described later. The third part 2 d isformed at an end at a side distant from the first part 2 b of the secondpart 2 c.

The semiconductor chip 3 is a device body part in which a powertransistor such as power MIS FET (Metal Insulator Semiconductor FieldEffect Transistor) is formed, and has a first surface (top) and a secondsurface (bottom), which are positioned at sides opposed to each other ina thickness direction. The first surface of the semiconductor chip 3 islocated at a side of the head of the metal cap 2 (bottom of the recess 2a). On the other hand, the second surface of the semiconductor chip 3 islocated at a side of the leg (mounting surface of the semiconductordevice 1A) of the metal cap 2. A drain electrode (upper electrode) DE isdisposed on the first surface of the semiconductor chip 3, and a gateelectrode (first lower electrode) GE and a source electrode (secondlower electrode) SE are disposed on the second surface of thesemiconductor chip 3. That is, the semiconductor chip 3 is in aconfiguration where the semiconductor chip 3 can radiate heat generatedduring operation of the chip from both the first surface and the secondsurface, which are located oppositely to each other. Thermal expansioncoefficient of the semiconductor chip 3 is, for example, about 3.0 to3.5 ppm/° C.

The drain electrode DE of the semiconductor chip 3 is a drain electrodeof the power MOS FET, and bonded and electrically connected to thebottom (first part 2 b) of the recess 2 a of the metal cap 2 via aconnecting material (connection material for connection the cap) 5 a.

The gate electrode GE of the semiconductor chip 3 is a gate electrode ofthe power MOS FET. A surface of the gate electrode GE, which faces themounting board, is disposed in a plane different from the surface of thethird part 2 d of the metal cap 2, which faces the mounting board, anddisposed with being displaced in a direction approaching the bottom ofthe recess 2 a with respect to a position of the surface of the thirdpart 2 d, which faces the mounting board. The gate electrode GE isbonded and electrically connected to a metal plate terminal for gate(first outer connection terminal) 6G via a connection material (firstconnection material) 5 b.

The source electrode SE of the semiconductor chip 3 is a sourceelectrode of the power MOS FET. A surface of the source electrode SE,which faces the mounting board, is disposed in a plane different fromthe surface of the third part 2 d of the metal cap 2, which faces themounting board, and disposed with being displaced in a directionapproaching the bottom of the recess 2 a with respect to the position ofthe surface of the third part 2 d, which faces the mounting board. Thesource electrode SE is bonded to a metal plate terminal for source(second outer connection terminal) 6S via a connection material (secondconnection material) 5 c.

The metal plate terminals 6G, 6S comprise a metal having excellentelectric conductivity, heat conductivity, and machinability such ascopper or copper alloys, and an exposed surfaces of them are appliedwith metal plating similarly as that applied on the surface of the metalcap 2. Thickness of the metal terminals 6G, 6S is, for example, about0.1 to 0.5 mm. The thermal expansion coefficient of the metal terminals6G, 6S is, for example, about 16 to 17 ppm/° C. The metal plate terminalfor gate 6G is an outer terminal for gate of the semiconductor device1A, and the metal plate terminal for source 6S is an outer terminal forsource of the semiconductor device 1A; and surfaces of the metal plateterminals 6G, 6S, which face the mounting board, are disposed in thesame plane as the surface of the third part 2 d of the metal cap 2,which faces the mounting board. That is, the semiconductor device 1A ofthe embodiment 1 is formed in a surface mounting structure having thethird part 2 d for drain terminal, the metal plate terminal 6G for gateterminal and the metal plate terminal 6S for source terminal on a backof the semiconductor device 1. A plane unit of the metal plate terminal6S is larger than that of the metal plate terminal 6G.

Here, in the case of the package configuration where the gate electrodeGE and source electrode SE of the semiconductor chip 3 are directly usedas outer terminals (outer connection terminals) without providing metalplate terminals 6G, 6S, as the patent literature 1, there is a problemthat the outer terminals for the gate and source of the semiconductordevice vary depending on the chip size of the semiconductor chip or thepositions or size of the gate and source electrodes of the semiconductorchip. That is, in the case that the gate and source electrodes of thesemiconductor chip are formed directly as the outer terminals for thegate and source of the semiconductor device, even in the samesemiconductor device, when the semiconductor chip varies, the positionsor size of the outer terminals for the gate and source of thesemiconductor device may also vary.

On the contrary, in the embodiment 1, the gate electrode GE and sourceelectrode SE of the semiconductor chip 3 are provided with the metalplate terminal for gate 6G and the metal plate terminal for source 6Svia the connection materials 5 b, 5 c, and the terminals are used asouter terminals of the semiconductor device 1, and then positions,shapes, and size of the metal plate terminals 6G, 6S are defined (madeversatile), which makes it possible that even if the chip size of thesemiconductor chip 3 and the positions and size of the gate electrode GEand source electrode SE of the semiconductor chip 3 vary, the positions,shapes, and size of the outer terminals of the semiconductor 1A do notvary, or constant. That is, the outer terminals of the semiconductor 1Acan be provided with versatility.

In the method where a metal strip is ultrasonic-bonded to an electrodeof the semiconductor chip, since the metal strip is subjected toultrasonic vibration in a heated condition for metal-to-metal bonding,large force is applied to the semiconductor chip, as a result thesemiconductor chip, which is formed from weak semiconductor, may becracked or broken, consequently the power MIS FET may be concernedlydamaged. On the contrary, in the embodiment 1, since the metal plateterminals 6G, 6S are bonded via the connection materials 5 b, 5 c, largeforce is not applied to the semiconductor chip 3 during bonding themetal plate terminals 6G, 6S. Therefore, when the metal plate terminals6G, 6S are bonded to the gate electrode GE and source electrode SE ofthe semiconductor chip 3, the semiconductor chip 3 may not be cracked orbroken, and the power MIS FET may not be damaged.

The connection members 5 a to 5 c are formed from adhesive such assilver (Ag) paste. A brazing material such as high-lead (Pb)-tin (Sn)solder having a melting point of at least 260° C. or gold (Au) can beused as another material for the connection members 5 a to 5 c. Theconnection members 5 a to 5 c have the same melting point. Theconnection members 5 b and 5 c are formed by coating in the same processas described later, and therefore comprise the same material and havethe same thickness. The connection member 5 a has a large thicknesscompared with the connection members 5 b and 5 c.

The resin sealing body 4 comprises, for example, a phenol-based curingagent, silicone rubber, and an epoxy-based thermosetting resin addedwith filler, and is filled in the recess 2 a of the metal cap 2 suchthat it covers approximately all the exposed part of the semiconductorchip 3 (including the side face of the semiconductor chip 3, theconnection material 5 a, a second surface side of the semiconductor chip3, and the connection materials 5 b, 5 c), but does not cover bottoms(mounting surfaces) of the metal plate terminals 6G, 6S forming theouter terminals for the gate and the drain.

Here, when the semiconductor chip 3 is not sealed by resin, or keptbare, a problem of environmental-stress resistance such as leakagedefect or corrosion may occur. An example of the leakage defect includesa defect of short-circuit defect, that is, since an n-type or p-typesemiconductor region is sometimes exposed particularly at an outercircumferential corner of the semiconductor chip 3, the semiconductorregion may contact to the metal cap 2 or an electrode portion throughconductive foreign materials and the like, leading to the defect ofshort circuit (area short). Therefore, the semiconductor chip 3 ispreferably sealed by resin, however, in the case of the packageconfiguration where the gate electrode GE and source electrode SE of thesemiconductor chip 3 are directly used as the outer terminals withoutproviding the metal plate terminals 6G, 6S, as the patent literature 1,when the semiconductor chip 3 as a whole is intended to be sealed,consequently surfaces of the gate electrode GE and the source electrodeSE may be also covered, or the surfaces of the gate electrode GE and thesource electrode SE may be contaminated, therefore filling control ofthe resin, or control of the surface level of the resin is difficult.Therefore, actually only about a side face of the semiconductor chip 3can be covered, consequently effects on sealing can not be sufficientlyobtained.

On the contrary, the embodiment 1 is in a configuration where the gateelectrode GE and the source electrode SE have the metal plate terminals6G, 6S forming the outer terminals for the gate and source of thesemiconductor device 1A via the connection materials 5 b, 5 c asdescribed above, and positions of the mounting surfaces of the metalterminals 6G, 6S are protruded with respect to the second surface(surface of a surface protection layer 7) of the semiconductor chip 3 bya level corresponding to thickness of the connection materials 5 b, 5 cand the metal terminals 6G, 6S. Thus, when the semiconductor chip 3 as awhole is covered with the resin sealing body 4, margin is given incontrolling the surface level (height position of a top) of the resinsealing body 4 only by the level corresponding to the thickness of theconnection materials 5 b, 5 c and the metal terminals 6G, 6S, whichenables loosening of accuracy in filling control of the resin sealingbody 4. Therefore, the semiconductor chip 3 as a whole is covered withthe resin sealing body 4 without covering, with the resin sealing body4, or contaminating the mounting surfaces of the metal terminals 6G, 6Sforming the outer terminals for the gate and source of the semiconductordevice 1A. Accordingly, since the problem of environmental-stressresistance such as leakage defect or corrosion can be avoided,reliability of the semiconductor device 1A can be improved compared withthe structure in which the semiconductor chip 3 is not sealed by resin.

Next, FIG. 5 is a side view showing an example of mounting thesemiconductor device of FIG. 1, FIG. 6 is a plan view of a top of thesemiconductor device of FIG. 5, and FIG. 7 is a cross section view alonga line X2-X2 of the semiconductor device of FIG. 6.

A mounting board 10 is formed, for example, from a printed circuit boardcomprising glass epoxy resin as an insulating material among wiringlayers. A plurality of electrodes 10E are disposed on a main surface ofthe mounting board 10. The electrodes 10E are electrically connected toone another appropriately through wiring lines within the mounting board10. The electrodes 10E and the wiring lines comprise, for example,cupper or cupper alloys. Thermal expansion coefficient of the mountingboard 10 is, for example, about 15 to 80 ppm/° C.

FIG. 5 exemplifies a case that the semiconductor device 1A of theembodiment 1 and another type of semiconductor device 11 are mounted onthe main surface of the mounting board 10. The semiconductor device 11is one having a plastic package structure of, for example, QFN (QuadFlat Non leaded Package) type, and a plurality of electrodes 11E areexposed from lower parts of four side faces of the device. Theelectrodes 11E are bonded and electrically connected to the electrodes10E on the mounting board 10 via the connection materials 5 d. A pitchof the electrodes 11E is made to be, for example, 0.65 mm or 0.5 mm inaddition to 1.27 mm.

The metal plate terminal 6G for the gate of the semiconductor device 1Aof the embodiment 1 is bonded and electrically connected to theelectrodes 10E on the mounting board via the connection materials 5 e(fourth connection material). The metal plate terminal 6S for the sourceof the semiconductor device 1A is bonded and electrically connected tothe electrodes 10E on the mounting board via the connection materials 5f (fifth connection material). Furthermore, the third part 2 d for thedrain of the semiconductor device 1A is bonded and electricallyconnected to the electrodes 10E on the mounting board via the connectionmaterials 5 g (sixth connection material). That is, the semiconductordevice 1A of the embodiment 1 is surface-mounted on the main surface ofthe mounting board 10.

The connection materials 5 e, 5 f and 5 g comprise, for example, asoldering material having a lead-free composition, and coated in thesame process as in the connection material 5 d. As the solderingmaterial having the lead-free composition, tin-silver-cupper (forexample, Sn-3Ag-0.5Cu; melting point of about 217° C.), tin-zinc (forexample, Sn-9Zn; melting point of about 199° C.), tin-zinc-bismuth (forexample, Sn-8Zn-3Bi; melting point of about 190° C.),tin-silver-bismuth-indium (Sn-3.5Ag-0.5Bi-8In; melting point of about206° C.), and tin-silver-cupper-indium (Sn-3Ag-0.5Cu-7In; melting pointof about 206° C.) can be exemplified.

Here, in the case of the configuration where the gate electrode GE andsource electrode SE of the semiconductor chip 3 are bonded to theelectrodes 10E of the mounting board 10 via the connection materials asthe patent literature 1, since the semiconductor chip 3 is directlyconnected to the mounting board 10 having a large thermal expansioncoefficient compared with the semiconductor chip 3, there is a problemthat large thermal stress due to difference in thermal expansioncoefficient is added to connection portions for connecting the sourceelectrode SE and gate electrode GE of the semiconductor chip 3 to theelectrodes 10E of the mounting board 10, and thus thermal fatigue occursearly in the connection portions, consequently the connection portionsare broken. Alternatively, the semiconductor chip 3 may be cracked.

On the contrary, in the embodiment 1, the connection portion between thegate electrode GE of the semiconductor chip 3 and the electrode 10E ofthe mounting board 10 is formed in a stacked configuration of theconnection material 5 b, metal plate terminal 6G, and connectionmaterial 5 e; and the connection portion between the source electrode SEof the semiconductor chip 3 and the electrode 10E of the mounting board10 is formed in a stacked configuration of the connection material 5 c,metal plate terminal 6S, and connection material 5 f. That is, theconnection materials 5 b, 5 e are provided on and under the metal plateterminal 6G, and the connection materials 5 c, 5 f are provided on andunder the metal plate terminal 6S. Thus, since the distance between thegate electrode GE or source electrode SE of the semiconductor chip 3,and the electrodes 10E of the mounting board 10 can be lengthened, thethermal stress applied to the connection portions for connecting thegate electrode GE and source electrode SE of the semiconductor chip 3 tothe electrodes 10E of the mounting board 10 can be reduced. Moreover, asmaterial of the metal plate terminals 6G, 6S, a metal material having athermal expansion coefficient in the middle of the thermal expansioncoefficient of the semiconductor chip 3 and the thermal expansioncoefficient of the mounting board 10 is used, thereby difference inthermal expansion coefficient between members can be reduced, thereforethe thermal stress applied to the connection portions for connecting thegate electrode GE and source electrode SE of the semiconductor chip 3 tothe electrodes 10E of the mounting board 10 can be reduced.Consequently, break in the connection portion between the semiconductordevice 1A and the mounting board 10 can be suppressed or prevented, andthus thermal fatigue life of the connection portion can be improved. Inaddition, cracks in the semiconductor chip 3 due to the thermal stresscan be suppressed or prevented. That is, in the embodiment 1, theconnection portion (connection material 5 b, metal plate terminal 6G andconnection material 5 e) between the gate electrode GE of thesemiconductor chip 3 and the electrode 10E of the mounting board 10 andthe connection portion (connection material 5 c, metal plate terminal 6Sand connection material 5 f) between the source electrode SE of thesemiconductor chip 3 and the electrode 10E of the mounting board 10 havea function of buffering the thermal stress caused by difference inthermal expansion coefficient between the semiconductor chip 3 and themounting board 10.

Here, to avoid the problem of thermal stress due to difference inthermal expansion coefficient between the semiconductor chip 3 and themounting board 10, increase in thickness of the connection materials 5e, 5 f and 5 g is considered as a method for lengthening the distancebetween the electrodes (gate electrode GE and source electrode SE) ofthe semiconductor chip 3 and the electrodes of the mounting board 10.However, while it is easy if only the semiconductor device 1A is mountedon the main surface of the mounting board 10, actually anothersemiconductor device 11 is also mounted on the main surface of themounting board 10 as the above, and increase in thickness of theconnection materials 5 d, 5 e, 5 f and 5 g leads to increase in amountof the connection materials 5 d coated on the electrodes 11E of thesemiconductor device 11, which is disposed at a small pitch, the defectof short circuit among the electrodes 11E adjacent to one anotherpossibly occurs by the connection materials 5 d. Thus, while it isconsidered that the connection material 5 d and the connection materials5 e, 5 f and 5 g are coated in different steps, such a process increasesthe number of steps, which concernedly causes increase in manufacturingtime or decrease in yield due to generation of foreign substances.

On the contrary, in the embodiment 1, by providing the metal plateterminals 6G, 6S, the distance between the electrodes (gate electrode GEand source electrode SE) of the semiconductor chip 3 and the electrodesof the mounting board 10 can be lengthened without increasing thicknessof the connection materials 5 d, 5 e, 5 f and 5 g. Accordingly, thethermal stress applied to the connection portions for connecting thegate electrode GE and source electrode SE of the semiconductor chip 3 tothe electrodes 10E of the mounting board 10 can be reduced withoutcausing short-circuit defect among adjacent electrodes 11E of thesemiconductor device 11. Moreover, since the connection materials 5 d, 5e, 5 f and 5 g can be coated in the same process, increase inmanufacturing time due to increase in the number of steps or thedecrease in yield due to generation of foreign substances can beavoided.

Next, an example of a configuration of the semiconductor chip 3 isdescribed according to FIG. 8 to FIG. 10. FIG. 8 is a plan view of asemiconductor chip forming the semiconductor device of the embodiment 1,FIG. 9 is a cross section view along a line X3-X3 of the semiconductorchip of FIG. 8, and FIG. 10 is an enlarged view of a power transistorcell of the semiconductor chip of FIG. 8. A sign Y in FIG. 8 indicates afirst direction, and a sign X indicates a second direction perpendicularto the first direction. Here, the first direction Y is a narrowdirection of the semiconductor chip, and a longitudinal (extending)direction of a gate electrode of a power MIS FET (Metal InsulatorSemiconductor Field Effect Transistor). The second direction X is alongitudinal direction of the semiconductor chip, and a narrow directionof the gate electrode of the power MIS FET. In FIG. 10, a sign Gindicates a gate of the power MIS FET, a sign S indicates a source ofthe power MIS FET, and a sign D indicates a drain of the power MIS FET.

The semiconductor chip 3 is formed, for example, in a flat andrectangular shape. A semiconductor substrate (hereinafter, simply calledsubstrate) 3A for forming the semiconductor chip 3 has a substrate part3S and an epitaxial layer 3EP formed on a main surface thereof. Thesubstrate part 3S comprises, for example, n⁺-type silicon (Si)single-crystal, and the epitaxial layer 3EP comprises n-type siliconsingle-crystal having higher resistivity than that of the substrate part3S.

The substrate 3A has the first and second surfaces as surfaces oppositeto each other in a thickness direction of the substrate. The firstsurface of the substrate 3A is a bottom of the substrate part 3S, and adrain electrode DE comprising, for example, gold (Au) as a mainelectrode material is disposed entirely on the first surface of thesubstrate 3A. The drain electrode DE is formed by stacking, for example,titanium (Ti), nickel (Ni) and gold in this order on the first surfaceof the substrate part 3S. On the other hand, the second surface of thesubstrate 3A is a top of the epitaxial layer 3EP, and a gate electrodeGE, gate fingers GF1, GF2, a source electrode SE, and a guard ring GRcomprising, for example, aluminum (Al) or aluminum alloys as a mainelectrode material are disposed as the uppermost wiring layer on thesecond surface of the substrate 3A.

The gate electrode GE is a lead electrode for the gate of the power MISFET, and disposed near a side of one end in the second direction X ofthe semiconductor chip 3 and at approximately the middle in the firstdirection Y The gate electrode GE is formed integrally with the gatefingers GF1, GF2. One gate finger GF1 extends from the gate electrode GEnear the one end side of the semiconductor chip 3 in the seconddirection X to a side of the other end of the semiconductor chip 3 inthe second direction X at the middle in the first direction Y such thatthe semiconductor chip 3 is divided into upper and lower halves. Theother gate finger GF2 extends from the gate electrode GE near the oneend side of the semiconductor chip 3 in the second direction X toneighborhood of the outer circumference of the semiconductor chip 3along the outer circumference, and terminates at a side of the other endof the semiconductor chip 3 in the second direction X.

The source electrodes SE are lead electrodes for the source of the powerMIS FET, and disposed in upper and lower areas of the central gatefinger GF1 each. Respective source electrodes SE are isolated from thegate electrode GE and the gate fingers GF1, GF2. Respective sourceelectrodes SE have the same planar shape and size, and are disposed suchthat they are symmetrical with respect to the gate finger GF1.Respective source electrodes SE are made as a rectangular patternelongated in the second direction X, and formed such that a planerdimension of them is larger than that of the gate electrode GE.

The surface protection layer 7 is formed as the uppermost insulatinglayer on the main surface of the semiconductor chip 3 such that itcovers the gate electrode GE, gate fingers GF1, GF2, source electrodesSE, and guard rings GR. Openings 13 are formed in part of the surfaceprotection layer 7, and the gate electrode GE and the source electrodeSE are partially exposed from the openings 13. The gate electrode GE andthe source electrode SE exposed from the openings 13 are connected withthe connection materials 5 b, 5 c.

In an element formation region enclosed by the gate fingers GF1, GF2 onthe main surface of the semiconductor chip 3, multiple small cells Qcare disposed with being connected parallel to one another to obtain highpower. As the cells Qc, a power MIS FET having a trench gateconfiguration (vertical type) is exemplified. Configuration of the cellQc of the power MIS FET having the trench gate configuration isdescribed.

The cell Qc is formed from an n-channel type, field effect transistor,and has an n⁺-type semiconductor region 15 for source provided on theepitaxial layer 3EP on the main surface of the substrate 3A, asemiconductor region for drain formed by the n⁺-type substrate part 3Sat a back side of the substrate 3A and the n-type epitaxial layer 3EP,and a p-type semiconductor region 16 for channel formation provided onthe epitaxial layer 3EP between the regions. The semiconductor region 15contains, for example, phosphorus (P) or arsenic (As), and thesemiconductor region 16 contains, for example, boron (B).

A plurality of trenches (first trench) 17 a extending in a directionperpendicular to the main surface of the substrate 3A are formed on themain surface (second surface) of the substrate 3A. Each of the trenches17 a is formed such that it penetrates the semiconductor region 15 forsource and the semiconductor region 16 for channel formation from themain surface of the substrate 3A and terminates at the semiconductorregion for drain (here, epitaxial layer 3EP).

Gate electrodes 19E are provided within the trenches 17 a via gateinsulating films 18. The gate insulating films 18 comprise, for example,silicon oxides (SiO₂ and the like), and has a thickness of, for example,about 50 nm. The gate electrodes 19E are control electrodes applied withvoltage for controlling operation of the power MIS FET, and comprise,for example, low resistant, polycrystalline silicon. Channels of thecells Qc of the power MIS FET are formed in the semiconductor regions 16for channel formation opposed to side faces of the gate electrodes 19Ein the trenches 17 a. That is, channel current of the cell Qc of thepower MIS FET flows in a thickness direction of the substrate 3Aperpendicular to the main surface of the substrate 3A along a side faceof the trench 17 a. The sign DP in FIG. 10 indicates a parasitic diode.

An interlayer insulating layer 20 is formed on the gate electrode 19E.The interlayer insulating layer 20 comprises, for example, a siliconoxide, and part of the outer circumference of the layer covers over atop of the semiconductor region 15 for source. The source electrode SEis formed on the interlayer insulating layer 20. The source electrode SEis formed in a stacking configuration of a relatively thin barrier metallayer and a relatively thick metal layer deposited thereon. The barriermetal layer comprises, for example, titanium tungsten (TiW), and thethick metal layer thereon comprises, for example, aluminum or aluminumalloys.

The source electrode SE is contacted and electrically connected to thetop of the semiconductor region 15 for source of the power MIS FETthrough a contact hole 21 a perforated in the interlayer insulatinglayer 20, the top being exposed from the hole. A trench (second trench)22, which extends in a direction perpendicular to the main surface(second surface) of the substrate 3A, and penetrates the semiconductorregion 15 for source and terminates at the semiconductor region 16 forchannel formation, is formed on the substrate 3A at a bottom of thecontact hole 21 a. The source electrode SE is contacted and electricallyconnected to the semiconductor region 15 for source through the sideface of the trench 22, and connected to a p⁺-type semiconductor region23 at a bottom of the trench 22, and therethrough electrically connectedto the semiconductor region 16 for channel formation. The p⁺-typesemiconductor region 23 contains, for example, boron.

The gate electrodes 19E are disposed, for example, in a stripe type.That is, a plurality of gate electrodes 19E extending in the firstdirection Y are disposed along the second direction X in an arrangedmanner on the main surface of the semiconductor chip 3. The gateelectrodes 19E are formed integrally with gate wiring lines 19L andelectrically connected thereto. The gate wiring lines 19L comprise, forexample, low resistant, polycrystalline silicon, and led out ontoinsulating layers 24 for isolation of the outer circumference of a groupof the cells Qc. The insulating layers 24 for isolation comprise, forexample, silicon oxides (SiO₂ and the like). While the gate wiring lines19L are covered with the interlayer insulating layers 20 in isolationregions, they are electrically connected to the gate fingers GF1, GF2through contact holes 21 b perforated in the interlayer insulatinglayers 20, and therethrough electrically connected to the gate electrodeGE. That is, the gate electrode GE is electrically connected to the gateelectrodes 19E through the gate fingers GF1, GF2 and the gate wiringlines 19L.

As shown in FIG. 9, an outer circumferential corner (corner formed at acrossing portion between the side face of the semiconductor chip 3 andthe second surface) of the semiconductor chip 3 is sometimes bared.Therefore, unless the corner is covered with the resin sealing body 4,the problem of leakage defect tends to occur. On the contrary, in theembodiment 1, the outer circumferential corner of the semiconductor chip3 is also covered with the resin sealing body 4 as described above.Thus, since the problem on the environmental-stress resistance such asleakage defect and corrosion can be avoided, reliability of thesemiconductor device 1A can be improved compared with the structurewhere the semiconductor chip 3 is not sealed by resin.

Next, an example of a circuit configured using the semiconductor device1A of the embodiment 1 is described. FIG. 11 shows an example of anon-insulated DC-DC converter 25 configured using the semiconductordevice 1A of the embodiment 1. The non-insulated DC-DC converter 25 is apower conversion circuit used in a power circuit of an electronic devicesuch as desktop personal computer, laptop computer, server, or gamemachine, and has a control circuit 26, power MIS FETs (first and second,field effect transistors) Q1 and Q2, SBD (Schottky Barrier Diode) D1,and an element such as coil L1 and condenser C1.

The control circuit 26 is a circuit that supplies a signal forcontrolling width of voltage-switch-ON (ON-time) of the power MIS FETsQ1, Q2, including a pulse width modulation (PWM) circuit. Output(terminal for control signal) of the control circuit 26 is electricallyconnected to gates of the power MIS FETs Q1, Q2 via driver circuits. Thedriver circuits are circuits that control gate potential of the powerMIS FETs Q1, Q2 according to the control signals supplied from thecontrol circuit 26 in order to control operation of the power MIS FETsQ1, Q2. The driver circuits are formed, for example, from CMOS invertercircuits.

The power MIS FETs Q1, Q2 are connected in series between a terminal(first power terminal) ET1 for supplying input power potential (firstpower potential) Vin and a terminal (second power terminal) forsupplying reference potential (second power potential) GND. That is, thepower MIS FET Q1 is provided such that a source/drain channel of it isconnected in series between the terminal ET1 and an output node (outputterminal) N1, and the power MIS FET Q2 is provided such that asource/drain channel of it is connected in series between the outputnode N1 and the terminal for supplying ground potential GND.Configurations of the power MIS FETs Q1, Q2 are assumed as theconfiguration of the semiconductor device 1A of the embodiment 1. Theinput power potential Vin is, for example, 5 to 12 V. The referencepotential GND is, for example, power potential lower than the inputpower potential, and for example, ground potential or 0 (zero) V.Operation frequency (frequency at turning on and off the power MIS FETsQ1, Q2) of the non-insulated DC-DC converter 25 is, for example, about 1MHZ.

The power MIS FET Q1 is a power transistor for a high side switch (highpotential side; first operation voltage), and has a switch function forstoring energy into the coil L1 that supplies power to the output of thenon-insulated DC-DC converter 25 (input of a load circuit 27). The powerMIS FET Q1 is formed from a vertical-type field effect transistor inwhich a channel is formed in a thickness direction of a chip. Accordingto investigation of the inventor, in the power MIS FET Q1 for high sideswitch, switching loss (turn-on loss and turn-off loss) appears to beincreased due to parasitic capacitance added to the power MIS FET as theoperation frequency of the non-insulated DC-DC converter 25 increases.Therefore, in a usual case, a horizontal-type field effect transistor inwhich a channel is formed along a main surface of the chip (surface in adirection perpendicular to the thickness direction of the chip) isdesirably used as the field effect transistor for high-side switch inthe light of the switching loss. The reason for this is becauseparasitic capacitance added between the gate and the drain (gateparasitic capacitance) can be reduced in the horizontal-type fieldeffect transistor, since an overlapped area between the gate electrodeand the drain region is small compared with the vertical-type fieldeffect transistor. However, regarding resistance (ON-resistance)generated during operation of the horizontal-type field effecttransistor, when a value that is about same as in the vertical-typefield effect transistor is intended to be obtained, a cell area of thehorizontal-type field effect transistor must be made large about two andhalf times or more of that of the vertical-type field effect transistor,which is disadvantageous for reduction in size of an element. On thecontrary, in the case of the vertical-type field effect transistor,channel width per unit area can be increased compared with thehorizontal-type field effect transistor, and thereby ON-resistance canbe reduced. That is, the power MIS FET Q1 for high-side switch is formedfrom the vertical-type field effect transistor, thereby reduction insize of an element can be realized, and package can be reduced in size.

On the other hand, the power MIS FET Q2, which is a power transistor fora low-side switch (low potential side: second operation voltage), is atransistor for rectification of the non-insulated DC-DC converter 25,and has a function of performing rectification by decreasing resistanceof the transistor in synchronization with a frequency from the controlcircuit 26. The power MIS FET Q2 is formed from the vertical-type powerMIS FET in which the channel is formed in the thickness direction of thechip similarly as the power MIS FET Q1. This is because of, for example,the following reason. FIG. 12 shows an example of a timing chart of asignal of the non-insulated DC-DC converter 25. Ton indicates pulsewidth while the power MIS FET Q1 for high-side switch is in an ON-state,and T indicates a pulse cycle. As shown in FIG. 12, in the power MIS FETQ2 for low-side switch, ON-time (time period while voltage is applied)is longer than that of the power MIS FET Q1 for high-side switch.Therefore, since loss due to ON-resistance looks large rather than theswitching loss in the power MIS FET Q2, use of the vertical-type fieldeffect transistor in which channel width per unit area can be increasedcompared with the horizontal-type field effect transistor isadvantageous, which is the reason for the above. That is, the power MISFET Q2 for low-side switch is formed from the vertical-type field effecttransistor, thereby the ON-resistance can be decreased, therefore evenif current flowing into the non-insulated DC-DC converter 25 isincreased, voltage conversion efficiency can be improved. In FIG. 12,VGS1 indicates voltage between the gate and source of the power MIS FETQ1, Id1 indicates drain current (channel current) of the power MIS FETQ1, VDS1 indicates voltage between the source and drain of the power MISFET Q1, VGS2 indicates voltage between the gate and source of the powerMIS FET Q2, Id2 indicates drain current (channel current) of the powerMIS FET Q2, and VDS2 indicates voltage between the source and drain ofthe power MIS FET Q2.

In the non-insulated DC-DC converter 25 of FIG. 11, the output node N1for externally supplying the output power potential is provided in themiddle of a wiring line connecting between the source of the power MISFET Q1 and the drain of the power MIS FET Q2. The output node N1 iselectrically connected to the coil L1 via an output wiring line, and inturn electrically connected to the load circuit 27 via the output wiringline.

The SBDD1 is electrically connected between the output wiring line forconnecting the output node N1 to the coil L1 and a terminal forsupplying reference potential GND such that it is parallel to the powerMIS FET Q2. The SBDD1 is a diode in which forward voltage Vf is lowerthan that of the parasitic diode DP of the power MIS FET Q2. In theSBDD1, an anode is electrically connected to the terminal for supplyingreference potential GND, and a cathode is electrically connected to theoutput wiring line for connecting between the coil L1 and the outputnode N1. By connecting the SBDD1 in such a manner, voltage drop duringdead time (see FIG. 12) when the power MIS FET is turned off is reduced,conduction loss in the diode can be decreased, and diode recovery losscan be decreased due to decrease in time of reverse recovery.

The condenser C1 is electrically connected between the output wiringline for connecting the coil L1 to the load circuit 27 and the terminalfor supplying reference potential GND. As the load circuit 27, CPU(Central Processing Unit) or DSP (Digital Signal Processor) of theelectronic device can be exemplified.

Such a non-insulated DC-DC converter 25 performs conversion of powervoltage by alternately switching on and off with being synchronized bythe power MIS FETs Q1, Q2. That is, when the power MIS FET Q1 forhigh-side switch is in the ON state, drain current (first current) Id1flows from a terminal ET1 electrically connected to the drain of thepower MIS FET Q1 to the output node N1 through the power MIS FET Q1; andwhen the power MIS FET Q1 for high-side switch is in a OFF state, draincurrent Id2 flows due to counter electromotive voltage of the coil L1.The power MIS FET Q2 for low-side switch is turned on during flowing ofthe drain current Id2, thereby voltage drop can be reduced. The draincurrent Id1 is large current, for example, about 20 A. A level of lossin such a non-insulated DC-DC converter 25 is larger in the order ofON-resistance loss, which is the largest, switching loss, drive loss,dead-time diode loss, and others; therefore decrease in ON-resistanceextremely contributes to improvement in efficiency.

Next, an example of a method for manufacturing the semiconductor device1A of the embodiment 1 is described according to FIG. 13 to FIG. 19. Theupper of each of FIG. 13 to FIG. 19 is a plan view of a bottom (leg)side of the semiconductor device 1A during a manufacturing process, andthe lower is a cross section view along a line X4-X4 of the upper each.

First, as shown in FIG. 13, the connection material 5 a is coated on thebottom of the recess 2 a of the metal cap 2 through a nozzle 30 a(coating process of connection material for cap connection). Theconnection material 5 a uses adhesive such as silver paste or a brazingmaterial such as high-lead/tin solder. While a method of coating theconnection material 5 a using the nozzles 30 a is exemplified here, themethod is not limited to this, for example, the connection material 5 acan be coated by a printing method.

Then, as shown in FIG. 14, the semiconductor chip 3 is mounted on thebottom of the recess 2 a of the metal cap 2 via the connection material5 a (semiconductor chip mounting process). At that time, the firstsurface of the semiconductor chip 3 on which the drain electrode DE wasformed is directed to the bottom of the recess 2 a of the metal cap 2,and the drain electrode DE of the semiconductor chip 3 is lightlypressed to the bottom of the recess 2 a of the metal cap 2 via theconnection material 5 a.

After that, as shown in FIG. 15, connection materials 5 b, 5 c arecoated on tops of the gate electrode GE and the source electrode SE ofthe semiconductor chip 3 through a nozzle 30 b (coating process of firstand second connection materials). The connection materials 5 b, 5 c usethe adhesive such as silver paste or the brazing material such ashigh-lead/tin solder.

Then, as shown in FIG. 16, metal plate terminals 6G, 6S are mounted onthe tops of the gate electrode GE and the source electrode SE of thesemiconductor chip 3 via the connection materials 5 b, 5 c respectively(mounting process of terminal for external connection). The metal plateterminals 6G, 6S comprise, for example, cupper or cupper alloys as amain material; and herein, as shown in the lower of FIG. 16, a casewhere mounting surfaces of the metal plate terminals 6G, 6S projectupward with respect to the mounting surface of the third part 2 d of themetal cap 2 is exemplified.

Then, as shown in FIG. 17, the connection materials 5 a to 5 c areheated to bond among respective members (connection material heating andformation process). At that time, when the connection materials 5 a to 5c comprise the silver paste, heating temperature is set to, for example,about 180° C. to 200° C. so that the silver paste is thermally cured.When the connection materials 5 a to 5 c comprise the brazing material,heating temperature is set to, for example, about 320° C. to 360° C. sothat the brazing material is fused. At that time, as shown in the lowerof FIG. 17, a flat pressing plate 31 is placed on both the mountingsurfaces of the third part 2 d of the metal cap 2 and the metal plateterminals 6G, 6S and then the metal plate terminals 6G, 6S are presseddownward, so that both the mounting surfaces of the third part 2 d ofthe metal cap 2 and the metal plate terminals 6G, 6S are positioned inthe same plane.

Then, as shown in FIG. 18, a liquid resin material 4L is dropped intothe recess 2 a of the metal cap 2 through a nozzle 30 c (sealingmaterial drop process). At that time, the liquid resin material 4L isdropped, for example, into a gap between the metal plate terminals 6G,6S and the recess 2 a of the metal cap 2. In addition, the liquid resinmaterial 4L is dropped into the recess 2 a such that at least the outercircumferential corner of the semiconductor chip 3 in the recess 2 a iscovered with the resin material 4L. In the embodiment 1, since the metalplate terminals 6G, 6S project with respect to the second surface of thesemiconductor chip 3, the resin material 4L can be easily poured intothe recess 2 a without covering or contaminating the metal plateterminals 6G, 6S by the resin material 4L.

Then, the resin material 4L is poured into the recess 2 a such that itcovers the whole surface including the side face of the semiconductorchip 3, the second surface, and the corner formed at the crossingportion between the side face and the second surface, and then as shownin FIG. 19, the whole body is heated so that the sealing material 4L iscured to from the resin sealing body 4 (sealing material curingprocess). Thus, the whole surface including the side face of thesemiconductor chip 3, the second surface, and the corner formed at thecrossing portion between the side face and the second surface is coveredwith the resin sealing body 4. Heating temperature at that time is, forexample, about 180° C. irrespective of types of the connection materials5 a to 5 c.

After that, exposed surfaces of the metal cap 2 and the metal plateterminals 6G, 6S are applied with, for example, the plating treatment(surface treatment process). In this way, the semiconductor device 1A ismanufactured. When the connection materials 5 a to 5 c comprise thesilver paste, the metal cap 2 and the metal plate terminals 6G, 6S inwhich palladium and gold are previously applied on surfaces in thisorder from the lower layer are used. When the connection materials 5 ato 5 c comprise the brazing material, metal plating such as lead-tinplating, tin-silver-cupper plating, or tin plating is applied in thesurface treatment process.

Embodiment 2

FIG. 20 is a plan view of a top of a semiconductor device of theembodiment 2, FIG. 21 is a side view of the semiconductor device of FIG.20, FIG. 22 is a plan view of a bottom of the semiconductor device ofFIG. 20, FIG. 23 is a cross section view along a line X5-X5 of thesemiconductor device of FIG. 20, and FIG. 24 is a cross section viewalong a line Y1-Y1 of the semiconductor device of FIG. 20.

In the semiconductor device 1B of the embodiment 2, a shallow recess 2 eextending in a direction of the first part (head and upper part) isformed at lower parts of side faces of both longitudinal sides of themetal cap 2, and the metal plate terminals 6G, 6S extend long along anarrow direction of the metal cap 2 compared with the case of theembodiment 1, and respective two ends of them in the extending directionare protruded (exposed) outside of the metal cap 2 through respectiverecesses 2 e at the lower parts of the side faces of both thelongitudinal sides of the metal cap 2. The metal plate terminals 6G, 6Sare formed in the flat and rectangular shape, and integrally have bodyportions 6G1, 6S1 and lead portions 6G2, 6S2 respectively. Thickness ofthe body portions 6G1, 6S1 is larger than that of the metal plateterminals 6G, 6S in the embodiment 1. The lead portions 6G2, 6S2 areformed by etching part of a base material of the metal plate terminals,and formed to have a small thickness compared with the body portions6G1, 6S1. Ends of the lead portions 6G2, 6S2 are exposed from the metalcap 2. Other configurations than the above are omitted to be describedbecause they are same as in the embodiment 1.

FIG. 25 is a plan view showing an example of mounting the semiconductordevice of FIG. 20, and FIG. 26 is a side view of the semiconductordevice of FIG. 25. Although only a mounting portion of the semiconductordevice 1B on the mounting board 10 is shown here, another semiconductordevice (electronic component) is also mounted on the mounting board 10similarly as the embodiment 1.

In the embodiment 2, the lead portions 6G2, 6S2 of the metal plateterminals 6G, 6S of the semiconductor device 1B are exposed outsidethrough the recesses 2 e in the side faces of the metal cap 2, andaspects of the connection materials 5 e, 5 f connected to the exposedlead portions 6G2, 6S2 can be visually confirmed. For example, when theconnection materials 5 e, 5 f comprise the brazing material such assolder, whether solder fillet necessary for improving connectionreliability is formed can be visually confirmed. That is, quality ofconnection condition between the metal plate terminals 6G, 6S and theelectrodes 10E on the mounting board 10 can be easily determined fromthe aspects of the connection materials 5 e, 5 f exposed through therecesses 2 e in the side faces of the metal cap 2.

Moreover, since the lead portions 6G2, 6S2 of the metal plate terminals6G, 6S of the semiconductor device 1B are exposed outside through therecesses 2 e in the side faces of the metal cap 2, a mounting directionof the semiconductor device 1B can be easily confirmed externally.Therefore, error in the mounting direction of the semiconductor device1B can be prevented. Although a top of the metal cap 2 can be added witha mark indicating the mounting direction, since the top of the metal cap2 is sometimes attached with a radiating fin, indiscriminate addition ofthe mark may cause reduction in heat radiation, therefore the mark isdesirably not added. In the embodiment 2, since the mounting directionof the semiconductor device 1B can be confirmed from the lead portions6G2, 6S2 of the metal plate terminals 6G, 6S exposed outside the metalcap 2, the top of the metal cap 2 need not be added with the mark, andthe radiating fin can be attached to the top of the metal cap 2 withoutreducing the heat radiation.

Furthermore, since surface area and volume of the metal plate terminals6G, 6S can be increased compared with the case of the embodiment 1,radiation of heat generated during operation of the semiconductor device1B can be improved compared with in the embodiment 1. Furthermore,ON-resistance of the semiconductor device 1B can be reduced comparedwith the embodiment 1 because of the same reason.

Next, an example of a method for manufacturing the semiconductor device1B of the embodiment 2 is described according to FIG. 27 to FIG. 30. Theupper of each of FIG. 27 to FIG. 30 is a plan view of a bottom (leg)side of the semiconductor device 1B during a manufacturing process, andthe lower is a cross section view along a line X6-X6 of the upper each.

First, the same processes as those described according to FIG. 13 toFIG. 15 of the embodiment 1 are performed using the metal cap 2 havingthe recess 2 e of the embodiment 2, and then as shown in FIG. 27, themetal plate terminals 6G, 6S are mounted on tops of the gate electrodeGE and source electrode SE of the semiconductor chip 3 via theconnection materials 5 b, 5 c respectively (mounting process of externalconnection terminal). Here, convex surfaces of the body portions 6G1,6S1 of the metal plate terminals 6G, 6S are directed to a side of thegate electrode GE and the source electrode SE. Again in this case, asshown in the lower of FIG. 27, a case where mounting surfaces of themetal plate terminals 6G, 6S are protruded upward with respect to themounting surface of the third part 2 d of the metal cap 2 isexemplified.

Then, as shown in FIG. 28, the connection materials 5 a to 5 c areheated to bond among respective members (connection material heating andformation process). Heating temperature at that time is same as thatdescribed according to FIG. 17 of the embodiment 1. Again in this case,as shown in the lower of FIG. 28, the flat pressing plate 31 is placedon both the mounting surfaces of the third part 2 d of the metal cap 2and the metal plate terminals 6G, 6S and then the metal plate terminals6G, 6S are pressed downward, so that both the mounting surfaces of thethird part 2 d of the metal cap 2 and the metal plate terminals 6G, 6Sare positioned in the same plane.

Then, as shown in FIG. 29, the liquid resin material 4L is dropped intothe recess 2 a of the metal cap 2 through the nozzle 30 c similarly asdescribed according to FIG. 18 of the embodiment 1 (sealing materialdrop process). Again in the embodiment 2, since the metal plateterminals 6G, 6S are protruded with respect to the second surface of thesemiconductor chip 3 as described above, the resin material 4L can beeasily poured into the recess 2 a without covering or contaminating themetal plate terminals 6G, 6S by the resin material 4L.

Then, the resin material 4L is poured into the recess 2 a such that itcovers the whole surface including the side face of the semiconductorchip 3, the second surface, and the corner formed at the crossingportion between the side face and the second surface, and then as shownin FIG. 30, the whole body is heated so that the sealing material 4L iscured to from the resin sealing body 4 (sealing material curingprocess). Thus, the whole surface including the side face of thesemiconductor chip 3, the second surface, and the corner formed at thecrossing portion between the side face and the second surface is coveredwith the resin sealing body 4. Heating temperature at that time is sameas that described according to FIG. 19 of the embodiment 1.

After that, exposed surfaces of the metal cap 2 and the metal plateterminals 6G, 6S are applied with the plating treatment similarly asdescribed in the embodiment 1 (surface treatment process), and thus thesemiconductor device 1B is manufactured.

Embodiment 3

FIG. 31 is a plan view of a top of a semiconductor device of theembodiment 3, FIG. 32 is a side view of the semiconductor device of FIG.31, and FIG. 33 is a plan view of a bottom of the semiconductor deviceof FIG. 31. A cross section view along a line X5-X5 of FIG. 31 is equalto that of FIG. 23, and a cross section view along a line Y1-Y1 of FIG.31 is equal to that of FIG. 24.

A semiconductor device 1C in the embodiment 3 is approximately equal tothat of the embodiment 2. It differs in that the lead portions 6G2, 6S2of the metal plate terminals 6G, 6S is small in width compared with thebody portions 6G1, 6S1. The metal plate terminal 6S has a plurality oflead portions 6S2 that extend from one body portion 6S1, and isgenerally formed into a comblike shape. A mounting condition of thesemiconductor device 1C is not different from that described in theembodiment 2 except for smaller width of the lead portions 6G2, 6S2,therefore diagrammatic representation and description of it are omitted.

Next, an example of a method for manufacturing the semiconductor device1C of the embodiment 3 is described according to FIG. 34 to FIG. 38. Theupper of each of FIG. 34 to FIG. 38 is a plan view of a bottom (leg)side of the semiconductor device 1C during a manufacturing process, andthe lower is a cross section view along a line X7-X7 of the upper each.

First, the same processes as those described according to FIG. 13 toFIG. 15 of the embodiment 1 are performed using the metal cap 2 havingthe recess 2 e of the embodiment 2, and then as shown in FIG. 34, themetal plate terminals 6G, 6S are mounted on the tops of the gateelectrode GE and source electrode SE of the semiconductor chip 3 via theconnection materials 5 b, 5 c respectively similarly as the embodiment 2(mounting process of external connection terminal). Here, the metalplate terminals 6G, 6S are integral with a frame 6F through the leadportions 6G2, 6S2.

Then, as shown in FIG. 35, the connection materials 5 a to 5 c areheated to bond among respective members (connection material heating andformation process). Heating temperature at that time is same as thatdescribed according to FIG. 17 of the embodiment 1. Again in this case,as shown in the lower of FIG. 35, the flat pressing plate 31 is placedon both the mounting surfaces of the third part 2 d of the metal cap 2and the metal plate terminals 6G, 6S, so that both the mounting surfacesof the third part 2 d and the metal plate terminals 6G, 6S arepositioned in the same plane.

Then, as shown in FIG. 36, the liquid resin material 4L is dropped intothe recess 2 a of the metal cap 2 through the nozzle 30 c similarly asdescribed according to FIG. 18 of the embodiment 1 (sealing materialdrop process). Again in the embodiment 3, similarly as described in theembodiments 1 and 2, the resin material 4L can be easily poured into therecess 2 a without covering or contaminating the metal plate terminals6G, 6S by the resin material 4L.

Then, the resin material 4L is poured into the recess 2 a such that itcovers the whole surface including the side face of the semiconductorchip 3, the second surface, and the corner formed at the crossingportion between the side face and the second surface, and then as shownin FIG. 37, the whole body is heated so that the sealing material 4L iscured to from the resin sealing body 4 (sealing material curingprocess). Thus, the whole surface including the side face of thesemiconductor chip 3, the second surface, and the corner formed at thecrossing portion between the side face and the second surface is coveredwith the resin sealing body 4. Heating temperature at that time is sameas that described according to FIG. 19 of the embodiment 1.

After that, exposed surfaces of the metal cap 2, metal plate terminals6G, 6S, and frame 6F are applied with the plating treatment similarly asdescribed in the embodiment 1 (surface treatment process), and then asshown in FIG. 38, the lead portions 6G2, 6S2 are cut off, thereby themetal plate terminals 6G, 6S are separated from the frame 6F (leadcut-off process), and thus the semiconductor device 1C is manufactured.

Hereinbefore, the invention made by the inventor has been describedspecifically according to the embodiments, however, it will beappreciated that the invention is not limited to the embodiments, andvarious modifications can be made within a scope without departing fromthe gist of the invention.

For example, while the case where the gate electrodes was arranged in astripe type was described in the embodiments 1 to 3, the arrangement isnot limited to this, and for example, the gate electrodes can bearranged in a lattice pattern or a mesh pattern, so called mesh type.Since gate density can be improved by arranging them in the mesh type,the ON-resistance can be further decreased. In addition, since gateresistance can be decreased, the switching loss can be also decreased.

While the case where the main material of the metal plate terminal(external connection terminal) was cupper was described in theembodiments 1 to 3, it is not limited to this, and for example, 42 alloy(Fe-42Ni; linear expansion coefficient is, for example, about 4 ppm/°C.) or CIC (Cu/Invar alloy (Fe-36Ni)/Cu; linear expansion coefficientis, for example, about 1.5 ppm/° C.) may be used. Such a material havinga linear expansion coefficient that is further close to the linearexpansion coefficient of silicon (about 3 ppm/° C.) is used, therebysince thermal stress applied to a connecting portion between thesemiconductor device and the mounting board can be reduced, life of theconnecting portion can be improved.

While the case where the power transistor was the power MIS FET wasdescribed in the embodiments 1 to 3, it is not limited to this, and thepower transistor can be variously modified, for example, the powertransistor may be the bipolar transistor or the IGBT (Insulated GateBipolar Transistor). In this case, the source electrode SE and the metalplate terminal for source 6S of the power MIS FET correspond to anemitter electrode and a metal plate terminal for emitter (externalconnection terminal) of the bipolar transistor or the IGBT; the gateelectrode GE and the metal plate terminal for gate 6G of the power MISFET correspond to a base electrode and a metal plate terminal for base(external connection terminal) of the bipolar transistor or a gateelectrode and a metal plate terminal for gate (external connectionterminal) of the IGBT respectively; and the drain electrode DE and theexternal terminal for drain (third part 2 d) of the power MIS FETcorrespond to a collector electrode and an external connection terminalfor collector of the bipolar transistor or the IGBT.

While the case where the invention made by mainly the inventor was usedfor a power circuit for driving CPU or DSP that was an application fieldas the background of the invention was described in the abovedescription, the invention is not limited thereto, and can be variouslyused. For example, it can be used for power circuits for driving othercircuits.

INDUSTRIAL APPLICABILITY

The invention can be used for manufacture of a semiconductor devicehaving a power transistor.

1.-21. (canceled)
 22. A method for manufacturing a semiconductor devicecomprising the steps of: (a) providing a conductive cap having an upperpart, a side part and a leg part; (b) mounting a semiconductor chip in aregion enclosed by the upper part and the side part of the conductivecap, the semiconductor chip having a first surface and a second surfaceopposite to each other, an upper electrode formed on the first surface,and first and second lower electrodes formed on the second surface; (c)covering the semiconductor chip in a resin sealing body, wherein thestep (b) includes the steps of: (b1) mounting the semiconductor chip ina region enclosed by the upper part and the side part of the conductivecap via a connection material for cap between the upper electrode of thesemiconductor chip and the upper part of the conductive cap; (b2)mounting first and second, external connection terminals on the firstand the second lower electrodes of the semiconductor chip via first andsecond connection materials respectively; and (b3) heating and meltingthe connection material for cap, the first connection material and thesecond connection material so that the upper electrode of thesemiconductor chip is bonded to the upper part of the conductive cap viathe connection material for cap, the first lower-electrode of thesemiconductor chip is bonded to the first external connection terminalvia the first connection material, and the second lower electrode of thesemiconductor chip is bonded to the second external connection terminalvia the second connection material, and wherein the step (c) includesthe steps of: (c1) filling the resin sealing body into the regionenclosed by the upper part and the side part of the conductive cap sothat the semiconductor chip is covered and the first and the second,external connection terminals are exposed, and (c2) heating and curingthe resin sealing body.
 23. The method for manufacturing thesemiconductor device according to claim 22, wherein in the step (b3), amounting-board opposing surface of the leg of the conductive cap, andmounting-board opposing surfaces of the first and the second, externalconnection terminals are disposed in the same plane.
 24. The method formanufacturing the semiconductor device according to claim 22, whereinthe first and the second, external connection terminals have a functionof loosening control of a surface level of the resin sealing body duringfilling the resin sealing body in the step (c1).
 25. The method formanufacturing the semiconductor device according to claim 22, whereinthe first and the second, external connection terminals have a functionof making an outer terminal of the semiconductor device to be versatile.26. The method for manufacturing the semiconductor device according toclaim 22, wherein the first external connection terminal, the secondexternal connection terminal, the first connection material, and thesecond connection material have a function of buffering thermal stressgenerated due to difference in thermal expansion coefficient between thesemiconductor chip and the mounting board.